1. Field of the Invention
The present invention relates to a semiconductor device and method of fabricating the same. More particularly, it relates to a stacked gate flash memory device that can achieve high memory cell capacity.
2. Description of the Related Art
Complementary metal oxide semiconductor (CMOS) memory is generally categorized into two groups: random access memory (RAM) and read only memory (ROM). RAM is a volatile memory, wherein the stored data is erased when power is turned off. On the contrary, turning off power does not affect the stored data in a ROM.
In the past few years, market share of ROM has been continuously expanding, and the type attracting the most attention has been flash memory. The fact that a single memory cell is electrically programmable and multiple memory cell blocks are electrically erasable allows flexible and convenient application, superior to electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM) and programmable read only memory (PROM). Furthermore, fabricating flash memory is cost effective. Having the above advantages, flash memory has been widely applied in consumer electronic products, such as digital cameras, digital video cameras, mobile phones, notebooks, personal stereos and personal digital assistants (PDA).
Since portability of these electrical consumer products is strongly prioritized by consumers, the size of the products must be minimal. As a result, capacity of flash memory must increase, and functions must be maximized while size thereof is continuously minimized. Having an increased amount of access data, capacity of memory cells has been enhanced from 4 to 256 MB, and even 1 G byte will become the market trend in the near future.
Hence, there is a need for a flash memory device with high memory cell capacity.